Universal shoe guide for a centerless grinding machine

ABSTRACT

The invention contemplates a universal fixture adjustably supporting a set of selectively locked spring-loaded pins which may be released to conform to the workpiece diameter to be supported, and which may be locked to retain the correct worksupport arc for the particular workpiece. Fixtures for internal grinding and for external grinding are shown.

United States Patent lnventors Appl. No.

Filed Patented Assignee Bertrand Collin New Britain;

Victor J. Baccaro, Southington, both 01, Conn.

Sept. 9, 1968 July 27, 1971 Textron Inc.

Providence, R.I.

UNIVERSAL SHOE GUIDE FOR A CENTERLESS GRINDING MACHINE 14 Claims, 5Drawing Figs.

U.S. Cl 51/103, 51/238 Int. Cl 1324b 5/18 Field oISearch 51/236,

238.1,103, 103 C, 103 WH [56] References Cited UNITED STATES PATENTS2,048,467 7/1936 Roehrn 51/103 2,478,607 8/1949 Theler et al 51/103Primary ExaminerTravis S. McGehee Attorney-Hopgood and CalimafdeABSTRACT: The invention contemplates a universal fixture adjustablysupporting a set of selectively locked spring-loaded pins which may bereleased to conform to the workpiece diameter to be supported, and whichmay be locked to retain the correct work-support arc for the particularworkpiece. Fixtures for internal grinding and for external grinding areshown.

UNIVERSAL SHOE GUIDE FOR A CENTERLESS GRINDING MACHINE In the field ofcenterless grinding, the workpiece must be supported by a shoe thatgenerally is provided with a workpiece-supporting contoured surfacesubstantially conforming to the outside surface circumference of theworkpiece after grinding. Such shoes require machining of a set ofroughing and finishing shoes for each different workpiece. This is acumbersome and uneconomical approach for centerless grindinginstallations requiring frequent workpiece changes.

It is therefore an object of this invention to provide a universalfixture for centerless grinding of a workpiece wherein machineadjustments and setup time as greatly simplified and quick workpiecechanges are made possible.

It is a further object to provide a universal fixture for the grindingof a workpiece with a minimum amount of wear and requiring a minimum ofadjustment during use.

Another object is to provide an improved workpiece support forcenterless grinding of any of a variety of workpiece sizes, wherein thesupport includes adapter elements which are releasable to conform to thesupport contour of the desired workpiece size and which are settable toretain the correct conforming contour. I

Other objects and various further features of the invention will bepointed out or will occur to those skilled in the art from a reading ofthe following specification in conjunction with the accompanyingdrawings. In said drawings which show, for illustrative purposes only,preferred forms of the invention:

FIG. 1 is a side elevation view ofa grinding fixture of the invention,shown applied to a grinding machine and workpiece, to illustrate anexternal-grinding situation;

FIG. 2 is an enlarged side view partially broken-away and in section ofthe universal shoe used in the fixture of FIG. I;

FIG. 3 is a front view of the shoe as viewed from the aspect 3-3 of FIG.2, part of the structure being broken-away and sectioned in the plane30-311 of FIG. 2;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3 toillustrate the mounting for an individual supporting pin used in theuniversal shoe; and

FIG. Sis a side view similar to FIG. I ofa complete grinding fixtureassembly for the grinding of an internal surface of a workpiece.

Briefly stated, the invention contemplates a universal fixture for thesupport of one among a variety of workpiece sizes to be centerlessground upon a given machine. The fixture adjustably carries a pluralityof selectively locked spring-loaded pins which may be released toconform to the workpiece diameter, and which may be locked to retain thecorrect worksupport are for the particular workpiece. The principle ofthe invention is applicable to external-grinding and to internalgrindingsituations.

In FIG I, a workpiece such as a bearing race ring is mounted in such amanner that it is supported by a universal shoe structure 12 and by avertically adjustable front shoe or roll 14, in working relation with agrinding wheel 16. The front shoe 14 is vertically adjustably mounted onupright member or standard 18. Rotation of the workpiece as well asrestriction of axial movement may be by a rotating magnetic chuck (notshown). Rotation of the workpiece is about axis 17 and the direction ofits rotation and that of the grinding wheel are as shown by the arrowsI9.

The universal shoe structure I2 is mounted on a supporting body 20. Body20 in turn is fixedly-mounted on a radial slide 22, the position ofwhich is controlled by a manually rotatable handle 21 and a lead screw24. The radial slide, in turn, is mounted on an axially movable baseplate 26 which is slidably mounted on a machine base 28. Base plate 26provides axial movement of the universal shoe structure I2 toaccommodate workpieces of different axial lengths. The upright member I8is attached to the base plate 26. While the shoe I4 could be a duplicateof the universal shoe I2, we find that in many cases this is notnecessary and in fact we prefer to employ a support roll, as shown, on astub shaft that is selectively positionable by means 18' along avertical adjustment slot 18".

The universal shoe structure includes a plurality of springloaded pins32 across whose tips the workpiece 10 slides. The pins 32 extendgenerally radially, and are shown set for definition (at their tips) ofa support are unique to the contour of the workpiece l0 and to theorientation of the shoe structure on supporting body 20. The tips of thepins 32 may be hard, as when made of carbide.

The universal shoe structure 12 is rotatably mounted about a pivot 34between the arms of a U-shaped vertical slide 36. A stop 38 is providedto limit the rotation of the shoe structure 12. Limited pivot action ofthe shoe structure is suggested by the double-pointed arrow 40.

In FIG. 2, the supporting body 20 is shown provided with a cantileverarm or bracket 42, in which two pivot-control lock screws 44 aremounted. These screws act on the adjacent body surface or edge 46 of thepivoted shoe structure 12. The directional lines of force applied by thescrews 44 straddle the pivot 34 so that the screws may both be used toprevent rotation of the shoe structure 12 as well as to control itsorientation. The arm 42 is further provided with an advancing screwmechanism 48 for controlling the vertical position of the U- shapedvertical slide 36 along the directional of the arrow 50.

The screw mechanism 48 comprises an advancing screw 52 in threadedrelationship with the cantilever arm 42 and having a nonthreaded end 54captured in a bore 56 of the vertical slide 36. The end 54 is providedwith a circumferential groove to receive a transverse retaining pin 58set in slide 36, thus permitting rotation of the screw 52 accompanied byvertical control of slide 36. A locknut 60 is provided to lock the screw52.

and may be secured in adjusted position, by setscrews 64. Mounting holesare provided in the supporting body 20 for mounting to radial slide 22.

The vertical slide 36 is shown in FIG. 3 with spaced arms or sidemembers 66-68 between which the universal shoe structure I2 is pivotallymounted; the pivot 34 is seen to comprise two like stud or pin portions34-34 on a common alignment. Studs 34-34 are respectively fixed to andcarried by retaining or sideplates 70-7I, constituting part of the bodystructure of the universal shoe 12. Plates 70-71 are releasably clampedto each other by screws 82. At the upper end, screws 82 seat in plate 71and engage threaded bores in an offset or shoulder portion 78 formingpart of the plate 70; similarly, an offset or shoulder 80 forming partof plate 71 accommodates screws 82, at the lower end of the body of shoe12.

The plates 70-7] jointly retain a plurality of assemblies to positionpins 32. These assemblies, and therefore also pins 32, are clamped bysetting screws 82. In each pin assembly (see FIG. 4), the pin 32 is theprojecting head of the screw, threaded at into a triangularly ortrapezoidally prismatic slide block 88, having convergent side faces 98.Adjacent pin assemblies abut along their convergent side faces, inalternating directions of convergence, thus placing the bases ofoddnumbered blocks in bottoming reference to the sideplate 70, and thebases of even numbered blocks in similar but oppositely directedbottoming reference to the sideplate 71. The sideplate shoulders 7880are provided with beveled undercuts I02l04 to match the adjacent slopeof the adjacent slide block, as will be understood. Upon take up of theclamp screws 82, the slide blocks 88 jam with a lateral spread which isultimately borne by the shoulders 7880, at undercuts 102- I04, at whichpoint a small clearance, as at 100, remains at the apex (or short side)of each trapezoid; when clamped, a clearance 10! also exists betweenshoulders 78-80 and the adjacent surfaces of plates 71-70, respectively.

As previously noted, each pin 32 is independently movable andresiliently urged outwardly, to permit automatic contour conformation.The extent of such guided displacement is best seen in FIG. 4, whereinthe slide block 88, when released from clamp action by screws 82, ismovable between the outer posi- The vertical slide 36 is guided at 62 insupporting body 20 tion shown and an inner position of abutment withcorresponding internal shoulder faces 86-87 on plates 70-7l; at theouter position shown, outer flanges 9697 on plates 70-71 determine thelimit of projection of pins 32. Spring means 94, located in a bore 92 ineach block 88 and located by pin means 96 on plate 71, constantly urgeall pins to the projecting position; only by the described clamp actionare pins 32 held back of the position shown in FIG. 4.

In the operation of the device, the pivot-lock screws 44 and the clampscrews 82 are loosened, and the pins 32 are brought into contact with anannular master gauge having an outside diameter corresponding to thedesired final ground external diameter of the workpiece, the mastergauge being magnetically chucked on the rotation axis 17 and in abuttingreference to the grinding wheel 16. The radial-positioning slide 22 isadvanced toward the master gauge, to an extent assuring positiveretraction of all the pins 32, thereby confirming that each pin willcontact the workpiece 10, with full conformation as to arcuate contour.If necessary, the shoe 14 is also vertically adjusted in reference tothe gauge and axis. Thereupon, the lock screws 44 and 82 are set, tosecure the pivot orientation of shoe 12 (about axis 34) and to clamp thepins 32. The gauge is then removed, and the grinding wheel 16 istraversed out of working position. The workpiece 10 may then be insertedas shown in FIG. 1, and the normal working traverse of grinding wheel 16may be started.

By providing each of the pins 32 with an end tip, of differentcurvature, the likelihood of their contacting the same circumferentialline on the workpiece is minimized. Alternatively, each of the pins maybe so variously offset on its individual slide block 88 so as to avoidcoincidence of their respective lines of contact with the workpiece.Both these techniques avoid excessive pressure along the same line ofthe workpiece.

FIG. shows a fixture assembly wherein the workpiece ring supported by amagnetic chuck (not shown) has an internal annular surface 106 to beground by a wheel 105, having grinding contact at 108. The internaldiameter of workpiece 10 is sufficiently large and the diameter of wheel105 is sufficiently small that it can be readily accommodated within theinner volume of the workpiece.

A universal shoe 12 is again provided to support the external surface ofthe workpiece l0, and in the form shown shoe 12 provides the mainvertical support of the workpiece. The shoe 12 is pivotally mounted at109 on a plate 110 which is vertically positionable with respect to themachine frame 111 to accommodate variations in radial thickness andexternal diameter of the workpiece.

The workpiece 10 of FIG. 5 is further supported by a stabilizing rollershoe 14 which is angularly spaced from the pins 32. The shoe 14 is shownmounted on a traverse slide 112; slide 112 is guided for positioningmovement along an arm 120 having pivoted reference (at 122) to themachine frame 111. The slide 112 is threaded at 114 to receive a leadscrew 116 which is joumaled into the bracket end 119 (of arm 120) andcontrolled by handle 118. A stay arm or adjustable link 126 is pivotallyrelated to the frame at 128 and may be clamped at 132 to the arm 120 atvarious selected locations along an adjustment slot 130, as dictated bythe nature of workpiece 10. It will be understood that the upright 120for supporting roller shoe 14 may be mountedwith the base plate 110, fortheir joint adjustable positioning, particularly for such axialpositioning as may be necessary for handling workpieces having differentaxial lengths.

The of the device of FIG. Sis essentially the same as in FIG. 1, exceptthat the universal shoe is brought into contact with the externaldiameter of the workpiece 10 instead of a master gauge. The pins 32 aredepressed to align along a circle conforming to the workpiece outsidediameter, and concentric with the workpiece drive axis. The shoe 14 ismade to contact the surface at some angular spacing from the pins 32,such that cradled support of the workpiece and of the grind-reactionforces is sustained between wide angularly spaced stabilizing limits;the base of support is preferably a substantial obtuse angle, less than180, as shown. After initiating the workpiece drive, the grinding wheelis traversed into working contact at 108, between the pins and thesupport 14. The contact point 108 may be anywhere between pins 32 andshoe 14 but is preferably placed just opposite the pins 32 closest tothe shoe 14 to provide a firrn support of the workpiece, so that theinternal surface 108 may be ground without deformation of the workpiece.1

While the present invention has been described in conjunction withpreferred embodiments, it may be modified without departing from thespirit and scope of the invention as defined by the claims.

We claim:

1. A fixture for centerless grinding of a rotated workpiece by agrinding wheel comprising a supporting body, a workpiece supporting shoestructure mounted on the supporting body and having a plurality ofindividually adjustable supporting pins mounted thereon, each pin beingadapted to provide at one end a localized support for the workpiece,said structure being pivotally mounted to said supporting body about anaxis generally parallel to the rotation axis of the workpiece, and meansoperative generally radially with respect to the workpiece rotation axisfor positioning said plurality of supportingpins to align the worksupporting ends thereof along the circumference of the workpiece.

2. A fixture for centerless grinding of a rotated workpiece by agrinding wheel, comprising: a supporting body, a workpiece-supportingshoe structure mounted on the supporting body and having a plurality ofindividually adjustable supporting pins mounted thereon, each pin beingadapted to provide at one end a localized support for the workpiece,said structure including a pair of retaining plates spaced from oneanother with said pins positioned therebetween for holding the pins inadjustably fixed position with respect to each other, and said structurebeing pivotally mounted to said supporting body about an axis generallyparallel to the rotation axis of the workpiece, and means operativegenerally radially with respect to the workpiece-rotation axis forpositioning said plurality of supporting pins to align the worksupporting ends thereof along the circumference of the workpiece.

3. The fixture as recited in claim 1 wherein the pivotal mounting forsaid shoe structure is provided by an upstanding bracket carried by saidbody, said bracket being adjustably positionable on said body.

4. The fixture as recited in claim 3 wherein said bracket is U-shapedwith upstanding arms and wherein said retaining plates are pivotallymounted between said upstanding arms.

5. The fixture as recited in claim 4 wherein said bracket is a slideguided by said body for selective generally vertical positioningdisplacement, and advancing-screw means coacting between the supportingbody and said bracket for vertical positioning control thereof.

6. The fixture as recited in claim 2 and further including a pair oflock screws mounted on the supporting body and acting on one of saidretaining plates, said screws being positioned on said supporting bodyto apply lines of force on said one retaining plate straddling the pivotaxis and providing controlled rotational orientation of the shoestructure.

7. The fixture of claim 2, wherein each supporting pin includes anelongated guide block guided for longitudinal displacement and from oneend of which the pin projects, and spring means independentlyresiliently urging each pin in the longitudinally outward direction.

8. The fixture of claim 7, in which each guide block is generallytrapezoidally prismatic, said blocks being retained by and between saidplates and arranged along an alignment transverse to the longitudinalpositioning alignments of said pins, the opposite converging sides ofone guide block being in side-by-side wedging contact with thecorresponding adjacent sides of the guide blocks adjacent thereto,adjacent blocks being arrayed in alternating opposite lateral directionsof con vergence, to permit locking of said blocks when said plates aredisplaced toward each other, and clamping means coacting between saidplates for drawing the same together.

9. The fixture as recited in claim 8, wherein the space between theretaining plates is so shaped to force a slight axial offset of saidblocks.

10. The fixture as recited in claim 9, wherein each retainer plate isprovided with a shoulder portion adjacent the opposite retainer plate,said shoulder portion having an effective height less than the effectivewidth of said blocks measured between the parallel faces thereof, saidclamping means being located at said shoulder portions.

11. The fixture as recited in claim 10, wherein said shoulder portionsare provided with undercut beveled sides facing said blocks, the slopeof said undercut sides substantially matching the slope of the adjacentblock face.'

12. The fixture as recited in claim 1, and further including a secondworkpiece-supporting shoe circumferentially spaced from the first shoestructure, and mounted on said body for movement generally transverse tothe adjustment axes ofsaid pins,

said second shoe being rotationally mounted on the fixture in the planesubstantially coincident with that of said first shoe structure, theworkpiece and the grinding wheel.

13. The fixture as recited in claim 12, wherein said body includes abase supporting plate supporting said shoe structure and movably mountedto the fixture for movement along a line in a plane substantiallycontaining the shoe structure, the workpiece and the grinding wheel.

14. The fixture as recited in claim 1, and further including lock screwmeans eoacting between the supporting body and said shoe structure forselectively controlling the pivoted orientation of the shoe structure.

1. A fixture for centerless grinding of a rotated workpiece by agrinding wheel comprising a supporting body, a workpiece supporting shoestructure mounted on the supporting body and having a plurality ofindividually adjustable supporting pins mounted thereon, each pin beingadapted to provide at one end a localized support for the workpiece,said structure being pivotally mounted to said supporting body about anaxis generally parallel to the rotation axis of the workpiece, and meansoperative generally radially with respect to the workpiece rotation axisfor positioning said plurality of supporting pins to align the worksupporting ends thereof along the circumference of the workpiece.
 2. Afixture for centerless grinding of a rotated workpiece by a grindingwheel, comprising: a supporting body, a workpiece-supporting shoestructure mounted on the supporting body and having a plurality ofindividually adjustable supporting pins mounted thereon, each pin beingadapted to provide at one end a localized support for the workpiece,said structure including a pair of retaining plates spaced from oneanother with said pins positioned therebetween for holding the pins inadjustably fixed position with respect to each other, and said structurebeing pivotally mounted to said supporting body about an axis generallyparallel to the rotation axis of the workpiece, and means operativegenerally radially with respect to the workpiece-rotation axis forpositioning said plurality of supporting pins to align the worksupporting ends thereof along the circumference of the workpiece.
 3. Thefixture as recited in claim 1 wherein the pivotal mounting for said shoestructure is provided by an upstanding bracket carried by said body,saId bracket being adjustably positionable on said body.
 4. The fixtureas recited in claim 3 wherein said bracket is U-shaped with upstandingarms and wherein said retaining plates are pivotally mounted betweensaid upstanding arms.
 5. The fixture as recited in claim 4 wherein saidbracket is a slide guided by said body for selective generally verticalpositioning displacement, and advancing-screw means coacting between thesupporting body and said bracket for vertical positioning controlthereof.
 6. The fixture as recited in claim 2 and further including apair of lock screws mounted on the supporting body and acting on one ofsaid retaining plates, said screws being positioned on said supportingbody to apply lines of force on said one retaining plate straddling thepivot axis and providing controlled rotational orientation of the shoestructure.
 7. The fixture of claim 2, wherein each supporting pinincludes an elongated guide block guided for longitudinal displacementand from one end of which the pin projects, and spring meansindependently resiliently urging each pin in the longitudinally outwarddirection.
 8. The fixture of claim 7, in which each guide block isgenerally trapezoidally prismatic, said blocks being retained by andbetween said plates and arranged along an alignment transverse to thelongitudinal positioning alignments of said pins, the oppositeconverging sides of one guide block being in side-by-side wedgingcontact with the corresponding adjacent sides of the guide blocksadjacent thereto, adjacent blocks being arrayed in alternating oppositelateral directions of convergence, to permit locking of said blocks whensaid plates are displaced toward each other, and clamping means coactingbetween said plates for drawing the same together.
 9. The fixture asrecited in claim 8, wherein the space between the retaining plates is soshaped to force a slight axial offset of said blocks.
 10. The fixture asrecited in claim 9, wherein each retainer plate is provided with ashoulder portion adjacent the opposite retainer plate, said shoulderportion having an effective height less than the effective width of saidblocks measured between the parallel faces thereof, said clamping meansbeing located at said shoulder portions.
 11. The fixture as recited inclaim 10, wherein said shoulder portions are provided with undercutbeveled sides facing said blocks, the slope of said undercut sidessubstantially matching the slope of the adjacent block face.
 12. Thefixture as recited in claim 1, and further including a secondworkpiece-supporting shoe circumferentially spaced from the first shoestructure, and mounted on said body for movement generally transverse tothe adjustment axes of said pins, said second shoe being rotationallymounted on the fixture in the plane substantially coincident with thatof said first shoe structure, the workpiece and the grinding wheel. 13.The fixture as recited in claim 12, wherein said body includes a basesupporting plate supporting said shoe structure and movably mounted tothe fixture for movement along a line in a plane substantiallycontaining the shoe structure, the workpiece and the grinding wheel. 14.The fixture as recited in claim 1, and further including lock screwmeans coacting between the supporting body and said shoe structure forselectively controlling the pivoted orientation of the shoe structure.